Xu S, et al. – The goal of the study described in this paper was to investigate the impacts of miR–891b on sensitizing breast cancer cells to alkylating chemotherapeutic drugs through Poly [ADP–ribose] polymerase (PARPs). The current study showed that MiR–891b increases the sensitivity of the breast cancer cells (HCC1806) to the cytotoxic impacts of the chemotherapeutic agent Methylnitronitrosoguanidine (MNNG) by suppressing the expression of PARP1.